A synthetic random basic copolymer with promiscuous binding to class II major histocompatibility complex molecules inhibits T-cell proliferative responses to major and minor histocompatibility antigens in vitro and confers the capacity to prevent murine graft-versus-host disease in vivo.

Graft-versus-host disease (GVHD) is a T-cell-mediated disease of transplanted donor T cells recognizing host alloantigens. Data presented in this report show, to our knowledge, for the first time that a synthetic copolymer of the amino acids L-Glu, L-Lys, L-Ala, and L-Tyr (molecular ratio, 1.9:6.0:4.7:1.0; Mr, 6000-8500) [corrected], termed GLAT, with promiscuous binding to multiple major histocompatibility complex class II alleles is capable of preventing lethal GVHD in the B10.D2 --> BALB/c model (both H-2d) across minor histocompatibility barriers. Administration of GLAT over a limited time after transplant significantly reduced the incidence, onset, and severity of disease. GLAT also improved long-term survival from lethal GVHD: 14/25 (56%) of experimental mice survived > 140 days after transplant compared to 2/26 of saline-treated or to 1/10 of hen egg lysozyme-treated control mice (P < 0.01). Long-term survivors were documented to be fully chimeric by PCR analysis of a polymorphic microsatellite region in the interleukin 1beta gene. In vitro, GLAT inhibited the mixed lymphocyte culture in a dose-dependent fashion across a variety of major barriers tested. Furthermore, GLAT inhibited the response of nylon wool-enriched T cells to syngeneic antigen-presenting cells presenting minor histocompatibility antigens. Prepulsing of the antigen-presenting cells with GLAT reduced the proliferative response, suggesting that GLAT inhibits antigen presentation.

Differential inducibility of HLA class I and II antigens by r-IFN gamma in type III bare lymphocyte syndrome.

Case Reports

Primary vascularization of the graft determines the immunodominance of murine minor H antigens during organ transplantation.

Grafts can be rejected even when matched for MHC because of differences in the minor histocompatibility Ags (mH-Ags). H4- and H60-derived epitopes are known as immunodominant mH-Ags in H2(b)-compatible BALB.B to C57BL/6 transplantation settings. Although multiple explanations have been provided to explain immunodominance of Ags, the role of vascularization of the graft is yet to be determined. In this study, we used heart (vascularized) and skin (nonvascularized) transplantations to determine the role of primary vascularization of the graft. A higher IFN-γ response toward H60 peptide occurs in heart recipients. In contrast, a higher IFN-γ response was generated against H4 peptide in skin transplant recipients. Peptide-loaded tetramer staining revealed a distinct antigenic hierarchy between heart and skin transplantation: H60-specific CD8(+) T cells were the most abundant after heart transplantation, whereas H4-specific CD8(+) T cells were more abundant after skin graft. Neither the tissue-specific distribution of mH-Ags nor the draining lymph node-derived dendritic cells correlated with the observed immunodominance. Interestingly, non-primarily vascularized cardiac allografts mimicked skin grafts in the observed immunodominance, and H60 immunodominance was observed in primarily vascularized skin grafts. However, T cell depletion from the BALB.B donor prior to cardiac allograft induces H4 immunodominance in vascularized cardiac allograft. Collectively, our data suggest that immediate transmigration of donor T cells via primary vascularization is responsible for the immunodominance of H60 mH-Ag in organ and tissue transplantation.

Impact of Leukocyte Function-Associated Antigen-1 Blockade on Endogenous Allospecific T Cells to Multiple Minor Histocompatibility Antigen Mismatched Cardiac Allograft.

BACKGROUND: Blocking leukocyte function-associated antigen (LFA)-1 in organ transplant recipients prolongs allograft survival. However, the precise mechanisms underlying the therapeutic potential of LFA-1 blockade in preventing chronic rejection are not fully elucidated. Cardiac allograft vasculopathy (CAV) is the preeminent cause of late cardiac allograft failure characterized histologically by concentric intimal hyperplasia. METHODS: Anti-LFA-1 monoclonal antibody was used in a multiple minor antigen-mismatched, BALB.B (H-2B) to C57BL/6 (H-2B), cardiac allograft model. Endogenous donor-specific CD8 T cells were tracked down using major histocompatibility complex multimers against the immunodominant H4, H7, H13, H28, and H60 minor Ags. RESULTS: The LFA-1 blockade prevented acute rejection and preserved palpable beating quality with reduced CD8 T-cell graft infiltration. Interestingly, less CD8 T cell infiltration was secondary to reduction of T-cell expansion rather than less trafficking. The LFA-1 blockade significantly suppressed the clonal expansion of minor histocompatibility antigen-specific CD8 T cells during the expansion and contraction phase. The CAV development was evaluated with morphometric analysis at postoperation day 100. The LFA-1 blockade profoundly attenuated neointimal hyperplasia (61.6 vs 23.8%; P < 0.05), CAV-affected vessel number (55.3 vs 15.9%; P < 0.05), and myocardial fibrosis (grade 3.29 vs 1.8; P < 0.05). Finally, short-term LFA-1 blockade promoted long-term donor-specific regulation, which resulted in attenuated transplant arteriosclerosis. CONCLUSIONS: Taken together, LFA-1 blockade inhibits initial endogenous alloreactive T-cell expansion and induces more regulation. Such a mechanism supports a pulse tolerance induction strategy with anti-LFA-1 rather than long-term treatment.

Narcolepsy: autoimmunity, effector T cell activation due to infection, or T cell independent, major histocompatibility complex class II induced neuronal loss?

Human narcolepsy with cataplexy is a neurological disorder, which develops due to a deficiency in hypocretin producing neurons in the hypothalamus. There is a strong association with human leucocyte antigens HLA-DR2 and HLA-DQB1*0602. The disease typically starts in adolescence. Recent developments in narcolepsy research support the hypothesis of narcolepsy being an immune-mediated disease. Narcolepsy is associated with polymorphisms of the genes encoding T cell receptor alpha chain, tumour necrosis factor alpha and tumour necrosis factor receptor II. Moreover the rate of streptococcal infection is increased at onset of narcolepsy. The hallmarks of anti-self reactions in the tissue--namely upregulation of major histocompatibility antigens and lymphocyte infiltrates--are missing in the hypothalamus. These findings are questionable because they were obtained by analyses performed many years after onset of disease. In some patients with narcolepsy autoantibodies to Tribbles homolog 2, which is expressed by hypocretin neurons, have been detected recently. Immune-mediated destruction of hypocretin producing neurons may be mediated by microglia/macrophages that become activated either by autoantigen specific CD4(+) T cells or superantigen stimulated CD8(+) T cells, or independent of T cells by activation of DQB1*0602 signalling. Activation of microglia and macrophages may lead to the release of neurotoxic molecules such as quinolinic acid, which has been shown to cause selective destruction of hypocretin neurons in the hypothalamus.

Genetic susceptibility to ankylosing spondylitis

Ankylosing spondylitis is a highly heritable, common rheumatic condition, primarily affecting the axial skeleton. The association with HLA-B27 has been demonstrated worldwide, and evidence for a role of HLA-B27 in disease comes from linkage and association studies in humans, and transgenic animal models. However, twin studies indicate that HLA-B27 contributes only 16% of the total genetic risk for disease. Furthermore, there is compelling evidence that non-B27 genes, both within and outwith the major histocompatability complex, are involved in disease aetiology. In this post-genomic era we have the tools to help elicit the genetic basis of disease. This review describes methods for genetic investigation of ankylosing spondylitis, and summarises the status of current research in this exciting area.

Genetics and the pathogenesis of ankylosing spondylitis

Purpose of review The field of genetic research in ankylosing spondylitis (AS) is advancing rapidly. The purpose of this review is to outline recent findings, particularly, in regard to genetic studies of the major histocompatibility complex (MHC) and the non-MHC genes IL23R, ERAP1, and killer cell immunologlobulin-like receptor (KIR) complex, in AS. Recent findings: Convincing evidence has been reported for the existence of further non-B27 MHC genes involved in AS. Strong, replicated association has been reported with IL23R and ERAP1 and AS. The IL23R finding strongly implicates the TH17 lymphocyte system in AS aetiopathogenesis. Suggestive evidence of a role for KIR gene polymorphism in AS exists, but definitive findings are awaited. Summary: The findings suggest that further genome-wide studies in large case-control cohorts are likely to be very productive in this disease. The IL23R findings and subsequent immunological investigations suggest that targeted intervention in the TH17 system is likely to have major therapeutic benefit, as it does in the genetically related diseases, inflammatory bowel disease and psoriasis.

Cloning and gastrointestinal expression of rat hephaestin: Relationship to other iron transport proteins

The membrane-bound ceruloplasmin homolog hephaestin plays a critical role in intestinal iron absorption. The aims of this study were to clone the rat hephaestin gene and to examine its expression in the gastrointestinal tract in relation to other genes encoding iron transport proteins. The rat hephaestin gene was isolated from intestinal mRNA and was found to encode a protein 96% identical to mouse hephaestin. Analysis by ribonuclease protection assay and Western blotting showed that hephaestin was expressed at high levels throughout the small intestine and colon. Immunofluorescence localized the hephaestin protein to the mature villus enterocytes with little or no expression in the crypts. Variations in iron status had a small but nonsignificant effect on hephaestin expression in the duodenum. The high sequence conservation between rat and mouse hephaestin is consistent with this protein playing a central role in intestinal iron absorption, although its precise function remains to be determined.

Targeting antigen to diverse APCs inactivates memory CD8+ T cells without eliciting tissue-destructive effector function

Memory T cells develop early during the preclinical stages of autoimmune diseases and have traditionally been considered resistant to tolerance induction. As such, they may represent a potent barrier to the successful immunotherapy of established autoimmune diseases. It was recently shown that memory CD8+ T cell responses are terminated when Ag is genetically targeted to steady-state dendritic cells. However, under these conditions, inactivation of memory CD8+ T cells is slow, allowing transiently expanded memory CD8+ T cells to exert tissue-destructive effector function. In this study, we compared different Ag-targeting strategies and show, using an MHC class II promoter to drive Ag expression in a diverse range of APCs, that CD8+ memory T cells can be rapidly inactivated by MHC class II+ hematopoietic APCs through a mechanism that involves a rapid and sustained downregulation of TCR, in which the effector response of CD8+ memory cells is rapidly truncated and Ag-expressing target tissue destruction is prevented. Our data provide the first demonstration that genetically targeting Ag to a broad range of MHC class II+ APC types is a highly efficient way to terminate memory CD8+ T cell responses to prevent tissue-destructive effector function and potentially established autoimmune diseases. Copyright © 2010 by The American Association of Immunologists, Inc.

Avaliação do PRA e CD30s no transplante renal intervivos. Acompanhamento no 1 ano e após 6 anos em pacientes do Hospital Federal de Bonsucesso (Rio de Janeiro, Brasil)

O CD30 solúvel (CD30s) é uma glicoproteína transmembrana da família do fator de necrose tumoral expressa na superfície das células T. Quando este marcador é clivado ele torna-se solúvel, sendo detectado na circulação. Atualmente, o valor de CD30s pré-transplante vem sido demonstrado como um bom preditor de rejeição aguda (RA) e perda do enxerto. Poucos estudos foram realizados para sua avaliação no pós-transplante e sua correlação com sobrevida e TFG. Avaliar a eficácia da determinação dos marcadores laboratoriais CD30 solúvel (CD30s) e anticorpos reativos contra painel HLA (PRA) em seis meses, um ano e seis anos pós-transplante renal em receptores de doadores vivos, correlacionando estes marcadores com episódios de rejeição aguda, eventos infecciosos no pós-transplante, perda do enxerto e óbito do paciente transplantado. E, avaliar a correlação destes marcadores com a sobrevida do enxerto renal nestes períodos. Os pacientes estudados foram transplantados renais com doadores vivos no Hospital Federal de Bonsucesso (HFB) do Rio de Janeiro no ano de 2006 e do período de agosto de 2010 a maio de 2011, sendo uma extensão de um trabalho realizado previamente. CD30s e PRA foram analisados nas amostras coletadas no pré-transplante e com 7, 14, 21 dias, 1, 3, 6, 12 meses após o transplante e nos pacientes transplantados em 2006 amostras após 6 anos de transplante. A taxa de filtração glomerular (TFG) foi estimada utilizando MDRD e CKD-epi e 6 meses, 1 ano e 6 anos após o transplante. Os pacientes foram agrupados em 5 grupos: sem eventos, com perda do enxerto, óbito, rejeição aguda e pacientes com quadros infecciosos. Estes grupos foram avaliados com relação ao CD30s, PRA I e II e comparados dois a dois. O teste qui quadrado foi utilizado. Quando necessário aplicou-se a correção de Yates, o teste de Fisher, o teste de Kruskal-wallis. Foi considerado estatisticamente significante p<0,05. As análises foram feitas pelo programa EPI-Info (versão 3.5.3). Setenta e seis pacientes com doadores vivos foram incluídos no estudo 47 pacientes não tiveram nenhum evento (grupo 1), 7 pacientes perderam o enxerto (grupo 2), 3 pacientes faleceram (grupo 3), 11 pacientes ficaram no grupo de rejeição aguda (grupo 4) e oito pacientes tiveram infecção por CMV e herpes (grupo 5). Os pacientes do grupo de RA tiveram correlação positiva com os valores tanto de CD30s Pré-transplante (p=0,01), quanto do CD30s pós-transplante (p=0,002) e PRA I e II (p<0,001), respectivamente, quando comparados com pacientes sem eventos. A TFG tanto com MDRD e CKD-Epi não mostrou correlação com CD30s pré e pós-transplante e nem PRA I e II. A TFG com as duas fórmulas foi menor no grupo com RA comparado com o grupo sem evento após 6 anos de transplante (p=0,006). CD30s é um bom preditor de RA, assim como PRAI e II. E, também mais uma ferramenta que pode ser utilizada no acompanhamento pós-transplante Renal. A RA é um preditor isolado para diminuição de TFG no transplante.

Differential T and B cell responses against Mycobacterium tuberculosis heparin-binding hemagglutinin adhesin in infected healthy individuals and patients with tuberculosis.

Because only 10% of individuals infected with Mycobacterium tuberculosis will eventually develop disease, antigens that are recognized differently by the immune systems of infected healthy and diseased subjects may constitute potential vaccine candidates. Here, the heparin-binding hemagglutinin adhesin (HBHA) is identified as such an antigen. Lymphocytes from 60% of healthy infected individuals (n=25) produced interferon (IFN)-gamma after stimulation with HBHA, compared with only 4% of patients with active tuberculosis (n=24). In the responders, both CD4(+) and CD8(+) cells secreted HBHA-specific IFN-gamma, and the antigen was presented by both major histocompatibility complex class I and II molecules. In contrast to the reduced ability of patients with tuberculosis to produce HBHA-specific IFN-gamma, most of them (82%) produced anti-HBHA antibodies, compared with 36% of the infected healthy subjects. These observations indicate that HBHA is recognized differently by the immune systems of patients with tuberculosis and infected healthy individuals and might provide a marker for protection against tuberculosis.

Corneal Allograft Rejection:Risk Factors, Diagnosis, Prevention, and Treatment

Recent advances in corneal graft technology, including donor tissue retrieval, storage and surgical techniques, have greatly improved the clinical outcome of corneal grafts. Despite these advances, immune mediated corneal graft rejection remains the single most important cause of corneal graft failure. Several host factors have been identified as conferring a "high risk" status to the host. These include: more than two quadrant vascularisation, with associated lymphatics, which augment the afferent and efferent arc of the immune response; herpes simplex keratitis; uveitis; silicone oil keratopathy; previous failed (rejected) grafts; "hot eyes"; young recipient age; and multiple surgical procedures at the time of grafting. Large grafts, by virtue of being closer to the host limbus, with its complement of vessels and antigen-presenting Langerhans cells, also are more susceptible to rejection. The diagnosis of graft rejection is entirely clinical and in its early stages the clinical signs could be subtle. Graft rejection is largely mediated by the major histocompatibility antigens, minor antigens and perhaps blood group ABO antigens and some cornea-specific antigens. Just as rejection is mediated by active immune mediated events, the lack of rejection (tolerance) is also sustained by active immune regulatory mechanisms. The anterior chamber associated immune deviation (ACAID) and probably, conjunctiva associated lymphoid tissue (CALT) induced mucosal tolerance, besides others, play an important role. Although graft rejection can lead to graft failure, most rejections can be readily controlled if appropriate management is commenced at the proper time. Topical steroids are the mainstay of graft rejection management. In the high-risk situations however, systemic steroids, and other immunosuppressive drugs such as cyclosporin and tacrolimus (FK506) are of proven benefit, both for treatment and prevention of rejection.

Effect of C282Y Genotype on Self-Reported Musculoskeletal Complications in Hereditary Hemochromatosis

OBJECTIVE: Arthropathy that mimics osteoarthritis (OA) and osteoporosis (OP) is considered a complication of hereditary hemochromatosis (HH). We have limited data comparing OA and OP prevalence among HH patients with different hemochromatosis type 1 (HFE) genotypes. We investigated the prevalence of OA and OP in patients with HH by C282Y homozygosity and compound heterozygosity (C282Y/H63D) genotype. METHODS: A total of 306 patients with HH completed a questionnaire. Clinical and demographic characteristics and presence of OA, OP and related complications were compared by genotype, adjusting for age, sex, body mass index (BMI), current smoking and menopausal status. RESULTS: In total, 266 of the 306 patients (87%) were homozygous for C282Y, and 40 (13%) were compound heterozygous. The 2 groups did not differ by median age [60 (interquartile range [IQR] 53 to 68) vs. 61 (55 to 67) years, P=0.8], sex (female: 48.8% vs. 37.5%, P=0.18) or current smoking habits (12.4% vs. 10%, P=0.3). As compared with compound heterozygous patients, C282Y homozygous patients had higher median serum ferritin concentration at diagnosis [1090 (IQR 610 to 2210) vs. 603 (362 to 950) µg/L, P<0.001], higher median transferrin saturation [80% (IQR 66 to 91%) vs. 63% (55 to 72%), P<0.001]) and lower median BMI [24.8 (22.1 to 26.9) vs. 26.2 (23.5 to 30.3) kg/m2, P<0.003]. The overall prevalence of self-reported OA was significantly higher with C282Y homozygosity than compound heterozygosity (53.4% vs. 32.5%; adjusted odds ratio [aOR] 2.4 [95% confidence interval 1.2-5.0]), as was self-reported OP (25.6% vs. 7.5%; aOR 3.5 [1.1-12.1]). CONCLUSION: Patients with C282Y homozygosity may be at increased risk of musculoskeletal complications of HH.

Cultured human fetal astrocytes can be induced by interferon-gamma to express HLA-DR.

Interferon-gamma (IFN-gamma) modulates the expression of Class II major histocompatibility antigens (MHC), thus providing a potential regulatory mechanism for local immune reactivity in the context of MHC-restricted antigen presentation. Within the central nervous system (CNS), the expression of MHC Class II antigens has been demonstrated on human reactive astrocytes and glioma cells. In order to investigate the modulation of HLA-DR on normal astrocytes, two cell lines were grown from a 20-week-old fetal brain. In situ none of the fetal brain cells expressed HLA-DR as determined by immunohistology on frozen tissue sections. The two cell lines, FB I and FB II, expressed GFAP indicating their astrocytic origin. FB I was HLA-DR negative at the first tissue culture passages, but could be induced to express HLA-DR when treated with 500 U/ml IFN-gamma. FB II was spontaneously HLA-DR positive in the early passages, lost the expression of this antigen after 11 passages and could also be induced to express HLA-DR by IFN-gamma. The induction of HLA-DR expression was demonstrated both by a binding RIA and by immunoprecipitation using a monoclonal antibody (MAB) directed against a monomorphic determinant of HLA-DR. The HLA-DR alloantigens were determined on FB II cells after IFN-gamma treatment, by immunofluorescence and by cytotoxicity assays, and were shown to be DR4, DR6, Drw52, DRw53 and DQwl. These results show that human fetal astrocytes can be induced to express HLA-DR by IFN-gamma in vitro and support the concept that astrocytes may function as antigen-presenting cells.

Direct binding of peptides to MHC class I molecules on living cells. Analysis at the single cell level.

To directly assess the binding of exogenous peptides to cell surface-associated MHC class I molecules at the single cell level, we examined the possibility of combining the use of biotinylated peptide derivatives with an immunofluorescence detection system based on flow cytometry. Various biotinylated derivatives of the adenovirus 5 early region 1A peptide 234-243, an antigenic peptide recognized by CTL in the context of H-2Db, were first screened in functional assays for their ability to bind efficiently to Db molecules on living cells. Suitable peptide derivatives were then tested for their ability to generate positive fluorescence signals upon addition of phycoerythrin-labeled streptavidin to peptide derivative-bearing cells. Strong fluorescent staining of Db-expressing cells was achieved after incubation with a peptide derivative containing a biotin group at the C-terminus. Competition experiments using the unmodified parental peptide as well as unrelated peptides known to bind to Kd, Kb, or Db, respectively, established that binding of the biotinylated peptide to living cells was Db-specific. By using Con A blasts derived from different H-2 congenic mouse strains, it could be shown that the biotinylated peptide bound only to Db among &gt; 20 class I alleles tested. Moreover, binding of the biotinylated peptide to cells expressing the Dbm13 and Dbm14 mutant molecules was drastically reduced compared to Db. Binding of the biotinylated peptide to freshly isolated Db+ cells was readily detectable, allowing direct assessment of the relative amount of peptide bound to distinct lymphocyte subpopulations by three-color flow cytometry. While minor differences between peripheral T and B cells could be documented, thymocytes were found to differ widely in their peptide binding activity. In all cases, these differences correlated positively with the differential expression of Db at the cell surface. Finally, kinetic studies at different temperatures strongly suggested that the biotinylated peptide first associated with Db molecules available constitutively at the cell surface and then with newly arrived Db molecules.